Adaptive chuck for planar bonding between substrates

Abstract

An electrostatic chuck includes an array of independently biased conductive chuck elements, an array of sensor-conductor assemblies, and / or a combination of an array of sensor-conductor assemblies and at least one motorized chuck. Conductive chuck elements, either standing alone or embedded in a sensor-conductor assembly, are independently biased electrostatically to compensate for bowing and / or warping of a substrate thereupon so that the substrate can be bonded with a planar surface. A single electrostatic chuck can be employed to reduce the bowing and warping of one of the two substrates to be bonded, or two electrostatic chucks can be employed to minimize the bowing and warping of two substrates to be bonded.

Description

BACKGROUND[0001]This invention relates to apparatuses for reducing bowing and warping in substrates during substrate bonding and methods of employing the same.[0002]Bonding of multiple substrates is required to enable three-dimensional integration of semiconductor chips. Through-substrate-via (TSV) structures, formed after multiple substrates are bonded and optionally thinned, provide electrical connection across the multiple substrates in a bonded structure including at least two semiconductor substrates. The bonded structure can be subsequently diced to provide stacked chips. Each stacked chip includes a plurality of semiconductor chips stacked in the vertical direction with electrical connection therebetween.[0003]Substrates are subject to local warping and bending due to internal stress. In the case of semiconductor substrates including many semiconductor devices composed of different semiconductor materials, insulator materials, and / or conductor materials and subjected to eleva...

AI Technical Summary

Benefits of technology

[0008]In another embodiment of the present invention, an electrostatic chuck includes an array of sensor-conductor assemblies. Each sensor-conductor assembly includes a conductive chuck element, a sensor configured to detect a substrate upon contact, and a motor that moves the sensor and the conductive chuck element vertically. The sensor detects the degree of deviation of the non-planar surface of a substrate from a planar surface. The conductive chuck element attached to each sensor-motor assembly is electrically biased by an electrostatic potential that is determined based on the detected deviation of the non-planar surface of the substrate from the planar surface at each sensor-motor assembly. The electrostatic bias voltage to the conductive chuck elements reduces the bowing and warping of the substrate for bonding. Alternately, a combination of an array of sensor-conductor assemblies and at least one motorized conductive chuck element can be employed to reduce the bowing and warping of a substrate for bonding.

Problems solved by technology

Substrates are subject to local warping and bending due to internal stress.

In general, the combination of global bowing and local warping in each semiconductor substrate generates gaps in bonded structures employed to form stacked chips.

Presence of such a gap in a bonded structure of two or more semiconductor substrates presents difficulties in subsequent processing by preventing formation of continuous through substrate vias or by allowing unintentional ingress of materials during planarization or wet processing steps.

Images